Method and apparatus for sound recording and reproducing



L. LUBEROFF Feb. 3, 1953 2 SHEETS-SHEET 1 Filed April 13, 1950 phoneMicro f agg Phone),

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METHOD AND APPARATUS .F OR SOUND RECORDING AND REPRODUCING Filed April13, 1950 2 SHEETS-SHEET 2 LICI. 3

IZi/fbior Louis Zuberojj atented Feb. 3, 1953 UNITED Ni" OFFICE .SMETHODAN D APPARATUS IFOR 'SOUND l RECORDING AND REPRODUCING Thisinventionrelates tothe recording and production of piano musiceitheraloneorrincombination withother instrumentalities as hereinafterdescribed.

The present 7 application is a continuation-inpart of my copendingapplication .Serial No. 609,747, filed August 9, .1945, now Patent No.2,530,251, issuedon, November 14, 1950.

One object of thepresent invention is to provide; an improved method andsystem. for recording piano, music.

fieretofo e, .it-has .beengthe practice to record piano music by meansof a microphone; which receives sounds by air conduction from the pianoand produces a corresponding electrical signal which is amplifiedandsupplied to .a recorder. This method of recording -does notresultinaccurate sound reproduction of piano music. A predoim'nantcharacteristic of thepiano is that it has a rapid tone decadence, andbecause of such action, themicrophone method of recording is notwellsuited for piano recording. Furthermore, thepoor acoustics of manyauditoriums and studios adverselyafiect recording by themicrophonemethod, especially in the case of large auditoriums and studios whereorchestra and piano concertos are performed and recorded. However,despite its disadvantages the microphone method has been used in thepast forwant of a better method.

In accordance with one aspect of the-present invention, there I isprovided .a method of piano recording which is entirely free of theshortcomings of the microphone method and which enables exact recordreproduction of piano music. According to this method, the physicalvibrations of the piano sounding board and for the associated stringsare translated-directly into an electrical signal which is amplified andsupplied to a recorder. .By this method, it, is possible to control theamplitude of the .signal through the use of hand or .kneeoperated volumecontrol means as hereinafter described. Furthermore, it is possible toutilize a combination-ofthis'method and the microphonemethod, withindividual gain controls for thesounding board pickupsand' themicrophone. Further still, in the preferred embodiment of the inventionprovision is made for utilizing a small portion of the signal asanaudible indicatin means duringcertainrecording operations involvingother instrumentalities. .as hereinafter describedbesides an electrical.visual decibel meter.

Another object of theinvention iseto providewa novel-syst m and.no ieldevices ior-improved re- '14 Claims. (Cl. 179-10011) 2 cording andproduction of .piano .music .either alone or in combination with. otherinstrumentalities.

The invention maybe fully understoodffrom-the following detaileddescription .with reference to the accompanying drawingswherein:

Fig. Us a front elevational view. of a'piano, embodying the presentinvention;

Fig. 2 is a diagrammatic illustration oftheelectrical system; and

Fig. 3 is a horizontal .sectionaleview showin .a preferred mountingofthepickeups.

, Referring firsttoFig. 1,.there is showna piano It whichmaybe of thecharacter disclosed in my appending ,application .Serial .No..5.3,808,';,filejd October 11, 1948. -Suchpiano-is oflthe spinet typeand it is provided with lid-closed compartments I I andiZ within whichthere are disposed respectively a recorder l3 and a phonograph J4. Thepiano is also provided with radio receiving apparatus, the tuningsection of which is centrally mounted as indicated at l5. Control knobs,designated generally by reference characterjfi, are provided to controlthe radio receiving. apparatus and alsoto controlthe.hand-operatedelements mentioned hereinafter. An audio frequencyamplifieris represented at 11. .At least oneloudspeaker is is provided,and if desired two loudspeakers or more maybe arranged as shown inFig. 1. A pair ofknee-operated levers l9 and 20 are also provided,thepurposeof which ,wilLappear presently.

It should be understood thatthe presentinvention is notlimitedto anyparticulardesign or type of,-piano,.that illustrated in Fi g. 11beingmerelyan example.

Referring nowto Fig. 2, thepiano sounding board, aportionof whichisshown at 2l,.has.associated therewith one or morepick-ups, there beingtwo pick-ups 22 and 22a shown in the illustration These pickeup s maybe. conventional electromagnetic or other type pick-upsandthey may beassociated with thesounding board itself and/ or with the strings (not,shown) inanysuit- -able'manner so as to respond tothephysicalviconnected to a double-throw *switch 26;which=operates intandem with a similar switch 21. The purpose of these switches is torender operative either a knee-operated volume control potentiometer 28or a hand-operated volume control potentiometer 29. Switch 21 isconnected to the input of audio amplifier l1, the output of which isconnected to double-throw switches 30 and 3| which may be tandemoperated. The sound reproducer or loudspeaker I8 is connected to theoutput of the audio amplifier |1 through stationary contacts of theswitches 30 and 3| and through resistors 32 and 33 connected as shown.The recorder I3 is connected as shown to stationary contacts of theswitches 30 and 3| through a transformer 34. A recording meter 35 isconnected to the recorder circuit. A power supply unit 36, controlled byon-off switch 31 serves to supply the necessary operating voltages tothe amplifiers H and 25.

, It will be seen from the illustration that the switches 30 and 3|serve in one position to shortcircuit the resistors 32 and 33, and inanother position to connect the recorder l3 to the output of the audioamplifier H. In the first-mentioned or upper position of the switches,the loud-speaker I8 is connected directly to the output of the audioamplifier l1, and the entire audio output of the amplifier is supplieddirectly to the loud-speaker. In the second or lower position of theswitches 30 and 3|, the recorder circuit is connected directly to theoutput of the audio amplifier, and at the same time the loud-speaker isconnected to the output of said amplifier through the resistors 32 and33. In this position of the switches, a predetermined percentage, e. g.twenty-five percent, of the audio output is supplied to the loudspeaker,while most of the audio output, 6. g. seventy-five percent, is suppliedto the recorder. The reduction of the output supplied to the loudspeakeris due to the fact that the resistors 32 and 33 limit the currentsupplied to the loudspeaker. The purpose of this arrangement will bedescribed presently.

If desired, the switch |3a which controls the driving motor for therecorder |3 may beganged with the switches 30 and 3| so that only onemanual operation is necessary to condition the apparatus for recording.

As hereinbefore mentioned, an important objectof the present inventionis to provide an improved method and apparatus for the recording ofpiano music. With the switch 23 closed, and with switches 30 and 3| inthe recording position, physical vibrations of the piano sounding board2| are translated directly into an electrical signal which is amplifiedand supplied to the recorder. This method of recording is a vastimprovement over the microphone method heretofore used. The pickups areindividually adjustable as to volume of their outputs by means of thepotentiometers 24. This is particularly advantageous if the pickups arearranged to respond predominantly to vibrations of differentfrequencies, e, g. treble and bass. During the recording operation, thevolume may be controlled by either of the devices 28 and 29. With theswitches 26 and 21 in the left-hand position, the knee-operated volumecontrol potentiometer 28 is efiective. This device is operated by one ofthe knee levers l9 and 20 (Fig. 1).. Thus the person playing the pianocan control the amplitude of the signal supplied to the recorder byactuating the knee lever while observing the recording meter. The kneelever may be spring biased toward the zero volume position, and byexerting knee pressure on the lever, the user may control the volume atwill. If desired, however, the volume may be adjusted by hand, in whichcas the switches 26 and 21 will be in the right-hand position and thevolume control potentiometer 29 will be effective.

It should be noted that the apparatus as thus far described is alsoadapted to function as an amplified piano. With switch 23 closed andwith switches 30 and 3! in the upper position, the vibrations of thepiano sounding board 2| are translated into an electrical signal whichis amplified and translated into sound possessing natural piano tone. Inthis case also the volume may be controlled as above described.

As shown in Fig. 2, the system is further arranged for use of thephonograph l4 and the radio receiver equipment l5, and a microphone 38is also preferably provided. The provision of these devicesgreatlyincreases the capabilities of the apparatus, as will be seenpresently.

The microphone 38 is connected through a volume control potentiometer 39and through a switch 49 to the input of the pre-amplifier 25. Not onlydoes the microphone make possible the recording of voice with Or withoutaccompaniment, but it enables recording of piano by a combination of themicrophone method and the method of the present invention, utilizing acommon amplifier for both. While the microphone method is not entirelysatisfactory when used alone, it may be used to advantage in combinationwith the pickup method of the present invention where the acoustics ofthe room do not seriously interfere.

The outputs of the phonograph l4 and the radio receiver equipment |5 areconnected to a selector switch 6|, which in turn is connected to adouble-throw switch 42, the latter being ganged with a second switch 43.Knee-operated and hand-operated volume control potentiometers 44 and 45are connected as shown to the switches 42 and 43 for selective inclusionin the circuit. The device 44 is actuated by one of the knee levers l9and 2|] in Fig. l. The switch 43 is connected to the input of the audioamplifier H which serves as a common audio amplifier for the variousinstrumentalities. The necessary power is supplied to the phonograph I4and the radio receiver equipment l5 from the power supply 36 throughonoff switches 46 and 41.

By means of the additional instrumentalities, the system is adapted forvarious uses in addition to the recording and reproduction of pianomusic. Thus, the piano may be utilized alone, either for recording orreproduction, or it may be used in combination with the other devices.For example, the piano may be played as an accompaniment to a phonographrecord, either for reproduction or recording. In this connection, itshould be noted that there are available phonograph records ofpiano-orchestra concertos and the like in which the piano part isomitted purputi-of-audio amplifier I -1f-isisupplied:to the loudspeaker, and -the reduced -'-sound :output of :the loudspeaker provideslow- "but audible reproduction of--voice,- radio program orphonographrendition being recorded. -At the same tim-e, this audiblereproduction is insumcient to-cause mechanical feedback to therecorder... cutter head. Thus loud .voice, radio or phonographpassagesmre.reproduced at low #audible 1eve'1 Wi-thoutcausing mechanicalfeedback, forexamplelwhencplaying in conjunction .-with the piano inconcerto style. Moreover the microphone control maybeset for high volumewithout causing howling dueeto acoustic feedback between theloudspeakerand the microphone, thus-.. permitting recording at highvolume without I recording i any extraneous howling effects.Furthermore, with respect to piano the large lBdlICtlOIl *output'iof theloud speaker likewiseprevents mechanical feedback-to recorder.

The system as illustrated provided awide variety of waysin which arecording-maybemade. These are as follows:

1. Piano may be recorded bythepickupmethod alone utilizing either handorknee-operated volume control.

2. Piano may be recorded by a-combinationof the pickup-and microphone.metho'ds utilizing either hand orknee-operated volume control.

3. Piano-and -either radio-or phonograph may be recorded, utilizing thepickup method alone for piano,- and utilizingeither hand orknee-operated volume control for-piano and'for radio or phonograph.

4. Piano and. either-'- radio or phonograph may be recorded, utilizing-acombination of the pickup and microphone methods for-piano.

5. The microphone maybe utilized torecord voice-alone ortorecordvoice-in combination with any of the other instrumentalities,utilizinghand or knee-operated volume control.

6. Radio orphonograph may berecorded alone, utilizing eitherhand-orknee-operated volume control.

The various instrumentalities -andvolume-controls actually providefourteen *ways in whicha recording may be'made.

The composite instrument provided by this inventionis usefulin aWa-rietyof placesand for a variety "of-purposes. 'Th'uS, it is useful in'theh0me,in places of "entertainment, 'ineducational institutionsretc.-For-scme-uses,*itmay be desirable to provide-for-coin oontrolled useoft-he instrument atcertain ti-m'es. --As shownin Fig."2, a conventionalcoin-control mechanism 48 maybe connectedin the-manner indicated, theswitch 31 being-a double-throw switch which may be placed in eitherposition. When placed in the righthand position, this --switch "willinclude the coin mechanism so that the instrument can be used only byinsertion of a coin to -close-a switch in the coin mechanism.

A further feature-of theinventionresides in the pick-up -arrangementand- 'mounting shown in Fig. 3. Aportion-ofthe'soundingboarddfl-adjacent the-'pick-up SDiscoVered-withalayer 51 of acoustically-absorptive soft material such as felt. Thisarrangement materiallyafiects the action of the pi'ck-upand providesimproved tonal quality. The resultis the preduction'ofa' predominantlypronounced fundamentalwith less corroborating harmonics'related'to thisfundamentaL-and also the lessening of prolongation 'of-the point ofdecadence. The-system and pick-up arrangement provide-a* very-flexiblemeans for obtaining the 6 most-Inaturalipianoftonebyls'ele'ctively mixingzthe frequencies and amplitudes. of thepick-cups.

As. shown in Fig. $3, the pick-.aupsfifl and 1 52 :are firmly heldrespectively .againstithelayer :51 and the sounding board"49iby:means;of;rigid brackets 53 and 54 secured to the .piano posts55,;56rand Eland carrying adjustablescrews 58 and 59 which engage disksfifl andfil. .Eachofithe pickaupsis enclosed a resilienturubbenhousing62'- :or-63 against which .the disktil or; filtbearstto hold the pick-upfirmlyv in place. .Inzoperatiori thppick-np armature is actuatedbyithesoundingboardewhile the rubber housing holds the pick upin placebyvirtue of its'being compressively heldbetween the board. and .thebacking disk or .plate. The housing also serves to'protect'thepickeup..By virtuezof'its resiliency the housing-.doesmot sinterfereiwith theboard vibrations.

'Thei ab'ove described*mountingtofvthe picksups eliminates so-called.wows which have been;encountered with priorvtypesof pick-.uptmountings,especially in notesof long sustainingaduration. Furthermore zthiSarrangement enablesreadyiadjustment'of frequency. As .the.screws 581or159 are tightened, the pick-up respondsincreasingly to higherfrequencies and .decreasingly to lower frequencies. Suchadjustmentenables; selective change of .the harmonic structuresofutheproducedsounds, and enables the :productionzoifdifferent tone characteristics.

From the foregoing description;itiwillzbei-zseen that .the inventionprovides a IIOYGL'QmBthQd and apparatus for piano recording, .and it:also provides a composite musical instrument whichhas wide capabilities.It will beunderstood, of course, that the invention is-notlimited totheparticular embodiment shown but 'is capable of various modifications andother embodiments.

I claim:

.1. In a system for ;electrically reproducing .or recordingmusic of apiano,'atleast'one-pick-up on the piano sounding board assemblyfortranslating physical vibrations directly into an electrical signal,means for amplifying:saidsignaLza sound'reproducer connected to saidamplifying means,'resistance means includedin circuit'with saidreproducer, ;a recorder, and switch :means adapted in one :position toshort circuit said resistance means and in another position to connectsaid .recorderto said amplifying means.

2. In a system 1 adapted ;for electrical grreproducing or :recording ofpiano music, and also adapted for electrical reproducing orxrecording ofradio, phonograph or.microphonerenditions; pick-up means on the pianosounding board-assembly for translating physical vibrations directlyinto an electrical .signal; yradio :receiving equipment; a phonograph;ami-crophone; :azcommon audio amplifier;meansxfor'selectively:connecting said pick-up means, saidradio receivingequipment, said phonograph and said microphone to the input of saidamplifier a recorderya sound reproducer; and means :for supplying :the.audio output of said amplifier either to said recorder or to saidreproducer; knee-operated volumecontrol means for controlling thesignals from said pick-up means and said microphone; and otherknee-operated volume control means for controlling the signals from saidradio receiving equipment and said phonograph.

3. In a systemadapted for electrical reproducing or recording of pianomusic, and also adapted for electrical reproducing or recording ofradio,phonograph or microphonerenditions; pick-up means on the piano soundingboardassembly for translating physical vibrations directlyinto anelectrical signal; radioreceiving equipment; a phonograph; a microphone;a common audio amplifier; means for selectively connecting said pick-upmeans, said radio receiving equipment, said phonograph and saidmicrophone to the input of said amplifier; a sound reproducer connectedto said amplifier; resistance means included in circuit with saidreproducer; a recorder; and switch means adapted in one position toshort circuit said resistance means and in another position to connectsaid recorder to said amplifier.

4. In a piano having a sound board, two selectively adjustableelectrical pick-ups mounted in cooperative association with said soundboard for picking up mechanical oscillationsthereof and converting saidoscillations into electrical impulses, means for amplifying saidelectrical impulses, a sound reproducer connected to said amplifyingmeans, means for mounting one pickup so as to effect translation of thesaid mechanical oscillations into their equivalents in electricalimpulses, means for damping the mechanical oscillations of a portion ofsaid sound board cor-responding to the mounting location of the secondpick-up, and means for mounting said second pick-up in cooperativeassociation with said portion of said board so as torespond to thedamped oscillations of said portion.

5. In a system adapted for electrical reproduction of piano music, andalso adapted for electrical reproduction of phonograph renditions;pick-up means on the piano sounding board assembly for translatingphysical vibrations directly into an electrical signal; a phonograph; acommon audio amplifier; means for selectively connecting said pick-upmeans and said phono graph to the input of said amplifier; a soundreproducer connected to the output of said amplifier; knee-operatedvolume control means for controlling the signal from said pick-up means;and other knee-operated volume control means for controlling the signalfrom said phonograph.

6. In a system adapted for electrical reproduction of piano music, andalso adapted for electrical reproduction of phonograph or microphonerenditions; pick-up means on the piano sounding board assembly fortranslating physical vibrations directly into an electrical signal; aphonograph; a microphone; a common audio amplifier; means forselectively connecting said pick-up means, said phonograph and saidmicrophone to the input of said amplifier; a sound reproducer connectedto the output of said ampliplifier; knee-operated volume control meansfor controlling the signals from said pick-up means and said microphone;and other knee-operated volume control means for controlling the signalfrom said phonograph.

7. In a system adapted for electrical reproduction of piano music, andalso adapted for electrical reproduction of phonograph renditions; atleast two pick-ups on the piano sounding board assembly for translatingphysical vibrations directly into an electrical signal; means forvarying the frequency response of each pick-up; a phonograph; a commonaudio amplifier; means for selectively connecting said pick-ups and saidphonograph to the input of said amplifier; a sound reproducer connectedto the output of said amplifier; knee-operated volume control means forcontrolling the signal from said pick-ups; and other knee-operatedvolume control means for controlling the signal from said phonograph.

8. 8. In a system adapted for electrical reproduction or recording ofpiano music, and also adapted for electrical reproduction or recordingof phonograph renditions; pick-up means on the piano sounding boardassembly for translating physical vibrations directly into an electricalsignal; a phonograph; a common audio amplifier; means for selectivelyconnecting said pickup means and said phonograph to the input of saidamplifier; a recorder; a sound reproducer; means for supplying the audiooutput of said amplifier either to said recorder or to said soundreproducer; knee-operated volume control means for controlling thesignal from said pick-up means; and other knee-operated volume controlmeansfor controlling the signal from said phonograph. V

9. Ina system adapted for electrical reproduction of piano music, andalso adapted for electrical reproduction of phonograph renditions;pick-up means on the piano sounding board assembly for translatingphysical vibrations directly into an electrical signal; a phonograph; acommon audio amplifier; means for selectively connecting said pick-upmeans and saidphonograph to the input of said amplifier; a soundreproducer connected to the output of said am plifier; and knee-operatedvolume control means for controlling the signal from said phonograph.10. In a system adapted for electrical reproduction of piano music,andalso adapted for electrical reproduction of phonograph renditions;pick-up means on the piano sounding board assembly for translatingphysical vibrations directly into an electrical signal; a phonograph; acommon audio amplifier; meansfor selectively connecting said pick-upmeans and said phonograph to the input of said amplifier; a soundreproducer connected to the output of said amplifier; hand-operatedvolume control means; kneeoperated volume control means, and means forconnecting either of said volume control means in circuit between saidphonograph and said amplifier for control of the amplitude of the signalfrom said phonograph.

11. Ina system adapted for electrical reproduction of piano music;pick-up means on the piano sounding board assembly for translatingphysical vibrations directly into an electrical signal; an audioamplifier; means for connecting said pick-up means to the input of saidamplifier; a sound reproducer connected to the output of said amplifier;hand-operated volume control means; knee-operated volume control means;and means for connecting either of said volume control means in circuitwith said pick up means and said amplifier iorecontrol of the amplitudeof said signal.

12. In a system adapted for electrical reproduction of piano music;pick-up means on the piano sounding board assembly for translatingphysical vibrations directly into an electrical signal; a microphone; anaudio amplifier; means for selectively connecting said pick-up means andsaid microphone to the input of said amplifier; a sound reproducerconnected to the output of said amplifier; hand-operated volume controlmeans; knee-operated volume control means; and means for connectingeither of said volume control means in circuit with said pick-up means,said microphone and said amplifier for control of the amplitudes of thesignals from said pick-up means and said microphone.

13. In a system adapted for electrical reproducing or recording of pianomusic, and also adapted for electrical reproducing or recording ofphonograph renditions; pick-up means on the piano sounding boardassembly for translating physical vibrations directly into an electricalsignal; a phonograph; a common audio amplifier; means for selectivelyconnecting said pick-up means and said phonograph to the input of saidamplifier; a sound reproducer connected to the output of said amplifier;resistance means included in circuit with said reproducer; a recorder;and switch means adapted in one position to short circuit saidresistance means and in another position to connect said recorder tosaid amplifier.

14. In a system adapted for electrical reproduction of piano music; atleast two pick-ups on the piano sounding board assembly for translatingphysical vibrations directly into an electrical signal; an audioamplifier having its input connected to said pick ups; a soundreproducer connected to the output' of said amplifier; means for varyingthe frequency response of each pickup; and knee-operatedsvolume controlmeans for controlling the signal from said pick-ups.

LOUIS LUBEROFF.

REFERENCES CITED The following references are of record-in the file ofthis patent:

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